Apparently not… …but here is a fix for you 
just created a Dark Sky icon sensor converter that converts Dark Sky icon to an actual mdi icon. It uses built in material icons from home assistant. If you are not using dark sky it shouldn’t be hard reengineering this template:
For this to work make sure you are pulling icon state from Dark Sky as follows
- platform: darksky
api_key: !secret darkskyapi
forecast:
- 0
monitored_conditions:
- icon
Add this to your sensors config. This will create a sensor called sensor.weather_just_icon it will have an mdi icon of current weather and will output the name of it as state
- platform: template
sensors:
weather_just_icon:
friendly_name: "mdi Real Weather Icon"
icon_template: >-
{% if is_state("sensor.dark_sky_icon","clear-day") %} mdi:weather-sunny
{% elif is_state("sensor.dark_sky_icon","clear-night") %} mdi:weather-night
{% elif is_state("sensor.dark_sky_icon","rain") %} mdi:weather-rainy
{% elif is_state("sensor.dark_sky_icon","snow") %} mdi:weather-snowy
{% elif is_state("sensor.dark_sky_icon","fog") %} mdi:weather-fog
{% elif is_state("sensor.dark_sky_icon","sleet") %} mdi:weather-partly-snowy-rainy
{% elif is_state("sensor.dark_sky_icon","wind") %} mdi:weather-windy
{% elif is_state("sensor.dark_sky_icon","cloudy") %} mdi:weather-cloudy
{% elif is_state("sensor.dark_sky_icon","partly-cloudy-day") %} mdi:weather-partly-cloudy
{% elif is_state("sensor.dark_sky_icon","partly-cloudy-night") %} mdi:weather-night-partly-cloudy
{% elif is_state("sensor.dark_sky_icon","hail") %} mdi:weather-hail
{% elif is_state("sensor.dark_sky_icon","lightning") %} mdi:weather-lightning
{% elif is_state("sensor.dark_sky_icon","thunderstorm") %} mdi:weather-lightning-rainy
{% endif %}
# entity_id: sensor.dark_sky_icon
value_template: >-
{% if is_state("sensor.dark_sky_icon","clear-day") %} weather-sunny
{% elif is_state("sensor.dark_sky_icon","clear-night") %} weather-night
{% elif is_state("sensor.dark_sky_icon","rain") %} weather-rainy
{% elif is_state("sensor.dark_sky_icon","snow") %} weather-snowy
{% elif is_state("sensor.dark_sky_icon","fog") %} weather-fog
{% elif is_state("sensor.dark_sky_icon","sleet") %} weather-partly-snowy-rainy
{% elif is_state("sensor.dark_sky_icon","wind") %} weather-windy
{% elif is_state("sensor.dark_sky_icon","cloudy") %} weather-cloudy
{% elif is_state("sensor.dark_sky_icon","partly-cloudy-day") %} weather-partly-cloudy
{% elif is_state("sensor.dark_sky_icon","partly-cloudy-night") %} weather-night-partly-cloudy
{% elif is_state("sensor.dark_sky_icon","hail") %} weather-hail
{% elif is_state("sensor.dark_sky_icon","lightning") %} weather-lightning
{% elif is_state("sensor.dark_sky_icon","thunderstorm") %} weather-lightning-rainy
{% endif %}